Question

An aqueous solution of glucose is 10%(w/v). The volume in which 1 mole of glucose is dissolved, will be:
A.180L
B.91L
C.0.91L
D.1.8L

Answer 1

Molarity is defined as the number of moles of solute dissolved in one litre or 1000 ml solution. The unit of molarity is moles per litre. Mathematically molarity is given as:
$Molarity = \dfrac{{{\text{No}}{\text{. of moles of solute}}}}{{{\text{volume of solution in litre}}}}$
Or
$Molarity = \dfrac{{{\text{No}}{\text{. of moles of solute}}}}{{{\text{volume of solution in ml}}}} \times 1000$

Complete step by step answer:
Here given that the weight/volume percentage of glucose is 10. That means in 100 ml of the volume of solution containing 10 grams of glucose. Now, let's find out the number of moles of glucose. As we know the number of moles of any substance is found, dividing the given mass of that substance by the molecular mass of that substance. The chemical formula for glucose is ${C_6}{H_{12}}{O_6}$ and hence the molecular mass of glucose can be calculated by the sum of all the atoms present in the formula of glucose. Hence the molecular mass of glucose is:
$6 \times 12 + 12 \times 1 + 6 \times 16$
$72 + 12 + 96 = 180g$
Here the mass of carbon is 12 grams, the mass of hydrogen is 1 gram, and the mass of oxygen is 16.$Number{\text{ }}of{\text{ }}moles{\text{ }}of{\text{ }}glucose = \dfrac{{{\text{Given mass of glucose}}}}{{{\text{molecular mass of glucose}}}}$
$\Rightarrow Number{\text{ }}of{\text{ }}moles{\text{ }}of{\text{ }}glucose = \dfrac{{10}}{{{\text{180}}}}$
$\Rightarrow Number{\text{ }}of{\text{ }}moles{\text{ }}of{\text{ }}glucose = \dfrac{1}{{18}}moles$
Now we will calculate the molarity of the solution which is given as:
$Molarity = \dfrac{1}{{18 \times 100}} \times 1000 = 0.555moles/ltr$
0.555 mole of glucose is present in 1000ml or 1 liter of solution. Then,
1 mole of glucose is present=$\dfrac{1}{{0.555}} = 1.8{\text{ }}ltr$
Hence the correct answer is option D.

Additional information: Glucose is a subcategory of carbohydrates and is made by plants during photosynthesis in the presence of water and carbon dioxide. It is another name for blood sugar and is one of the most preferred sources of fuel in the human body.

Note:
Molarity is used to measure the concentration of the chemical solution. But it is not considered to be the best method for the measurement of concentration because molarity depends upon the temperature. As the temperature changes, there is a change observed in molarity.